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Clinical Pathology > Platelets and Coagulation > Flashcards

Platelets and Coagulation Flashcards

1
Q

Describe the platelet number in general terms?

A
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2
Q

Formula for platelet # estimation.

A

Average # platelets in 10 fields x 20,000= #/uL

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3
Q

What two dog breeds usually have lower platelets numbers?

A

greyhounds

Cavalier King Charles spaniels

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4
Q

Describes the levels of platelets for mild, moderate, severe thrombocytopenia?

A
  • Mild® 80,000-100,000/uL (marrow dz or consumption)
  • Moderate® 40,000-80,000/uL (marrow dz/consumption)
    • severe® <20,000-30,000/uL (marrow dz or destruction)
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5
Q

What is the main clinical sign of thrombocytopenia?

A

subcuntaneous/mucosal bleeding

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6
Q

What are the main classification of the causes of thrombocytopenia?

A
  1. peripheral
    a. increased destruction
    b. increased consumption
    c. abnormal distribution
  2. Bone marrow problem: decreased production
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7
Q

If an equine has thrombocytopenia and a bone marrow aspirate was taken, what is the likely diagnosis?

A

neoplasia

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8
Q

What does the picture show? What is it an appropriate response to?

A

Megakaryocytic hyperplasia-appropiate response to thrombocytopenia

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9
Q

What hematology abnormality does bracken fern posioning in cattle cause?

A

thrombocytopenia- disrupt production in the bone marrow

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10
Q

What infection causes cyclic thrombocytopenia and is known to infect platelets?

A

Anaplasma platys

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11
Q

A patient comes in 3-10days after being vaccinated with a modifed-live vaccine for surgery. What hematology index will be low? Should we pocede with surgery?

A

thrombocytopenia- wait more than 2 weeks to do surery

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12
Q

What is the inclusion?

A
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13
Q

A dog presents with thrombocytosis and the blood film below. What is the likely cause?

A

neoplasia (tumor in platelet)- may be primary thrombocytosis from neoplastic disease

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14
Q

What are the secondary causes of thrombocytosis?

A
  • Iron-deficiency anemia; blood loss iron deficiency anemia
  • Hypercortisolemia
  • Inflammation® typically chronic
  • Vinca alkaloids
  • Post-splenectomy
  • Rebound:
    • after severe acute hemorrhage;
    • ending myelosuppression
    • resolution of immune-mediated thrombocytopenia
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15
Q

What happens to platelets levels after a splenectomy?

A

increase (thrombocytosis)

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16
Q

If there is an platelet type bleeding but the platelet level is normal and coagulation is normal, what is the best test to perform?

A

BMBT

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17
Q

What are the minimum platelets levels for most species and horses?

A

most species 7-10 platelets/100x hpf

horses 4-10 platelets/100x

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18
Q

What are the acquire causes of thrombopathia?

A
  • ­fibrin degradation products inhibit platelet function (DIC)
  • Drugs
    • NSAIDs (aspirin, acetaminophen, phenylbutazone)
    • anesthetics
    • Bronchodilators
    • Calcium channel blockers
  • Renal failure
  • Hyperglobulinemia
    • Plasma cell neoplasia (multiple myeloma)
    • Chronic ehrlichiosis
  • immune-mediated thrombocytopenia
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19
Q

What are the congenital causes of a thrombopathia?

A
  1. von Willegrand’s disease
  2. rare intrinsic platelet defects
20
Q

What are the vitamin K dependent coagulation factors?

A

2 (thrombin), 7, 9, 10

21
Q

What are two ways vitamin K can become deficient?

A

rodenticide toxicity

maldigestion

22
Q

What is the vitamin K factor with the shortest half-life?

A

factor 7

23
Q

What event in the coagulation cascade leads to the formation of a stable fibrin clot?

A

thrombin burst

24
Q

What factor is activated to form cross-linked monomers of fibrin in the clot?

A

Factor 13

25
Q

what are the important regulatory proteins of hemostasis?

A
  • Plasmin
    • Degrades fibrinogen, fibrin, crosslinked fibrin
  • Antithrombin 3
    • Inhibits thrombin, factor 10a, factor 9a, and others
  • Protein C with protein S
    • Inhibits factor 5a, factor 8a
  • Tissue factor pathway inhibitor (TFPI)
    • Inhibits factor 7a and factor 1
  • Tissue plasminogen activator- catalyzes plasminogen®plasmin rxn
26
Q

What coagulation factors are consumed when blood clots and lacking in serum? Is serum good to use for coagulation testing?

A

Factor 5 & 8

NO

27
Q

What should the ratio of citrate:blood be for coagulation testing?

A

1:9

28
Q

What is PT?

A

prothrombin time-measured extrinsic coagulaton cascade

  • Time for fibrin clot to form in citrated-plasma after adding*:
    • Tissue factor (thromboplastin)
    • Ca
    • A substitute for activated platelet phospholipid
29
Q

What is PTT?

A

activated partial thromboplastin time- measures intrinsic cascade and common pathway

  • Measures time for fibrin clot to form in citrated-plasma after adding
    • A contact activator
    • Ca
    • Substitute for activated platelet phospholipid
30
Q

What are the two common issues that can cause the PTT to be artifactually increased?

A
  1. delayed testing and/or warming of the sample
  2. low plasma to citrate (aka short filled tube or erythrocytosis)
31
Q

What does an elevated fibrinogen indicate?

A

inflammation

32
Q

How can you differentiate from platelet vs coagulopathy type bleeding? Can you use petechiation as a definitive difference?

A

platelets- small bleeds, mucosal hemorrhage/petechiation

coag- major, dramatic bleeding, involving organs sometimes, joint spaces, SQ, petechiae may be present-not deciding factor

33
Q

Which of the hemophilias are sex-linked? What sex are they more common in?

A

Hemophilia A (F8) and B (F9)

males

34
Q

What are the differntials for increased consumption of platelets?

A

DIC

microangiopathic dz

vasculitis/endocarditis

envenomation

35
Q

What infectious disease is known to supress the bone marrow?

A

ehrlichia

36
Q

What are drugs/toxins that can supress the bone marrow?

A

anticancer chemotherapy drugs

bracken fern

estrogen

37
Q

What are the differentials that cause decreased bone marrow production of platelets?

A

immune-mediated/idiopathic

marrow-replacement-neoplasia/fibrosis

infectious dz

drugs & toxins

radiation

38
Q

What are causes of secondary thrombocytosis?

A

redistribution

increased prodcuction-

Fe-def anemia

rebound

hypercotisolemia

inflammation

vinca alkaloids

post-splenectomy

rebound

39
Q

Name three reasons for a prolonged BMBT.

A
  1. thrombocytopenia
  2. vascular defect
  3. thrombopathia
40
Q

Differentials for acquired thrombopathia?

A

increased FDP

drugs

renal failure

hyperglobulinemia

41
Q

Differentails for congenital thrombopathia?

A

von Willebrand’s dz

rare intrinsic platelet dz

42
Q

What is the function of factor 12, HMWK, and PK?

A

kinin in inflammation-WBC attractacts & pain

complement activation

activation fibrinolysis

43
Q

What do you add to the test tube for a PT test? What does a prolonged PT test indicate?

A

Add Ca, TFIII, susbstitute for activate platelet phospholipid

inhibition/def factor 7 or common pathway factors

44
Q

What do you add to the test tube for a PTT test? What does a prolonged PTT test indicate?

A

Add- contact activator, Ca, substitute for activated platelet phospholipid

inhibition/def intrinsic/common pathway factors

45
Q

What deficiency do you need to see prolonged ACT?

A

95%

46
Q

If D-dimers normal, but elevated FDP- what does that indicate?

A

increased fibrinogenolysis

47
Q

Why would there be decreased clearance of FDP and D-dimers?

A

hepatic failure

Clinical Pathology (6 decks)

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